It is, of course, very difficult to know for sure why any particular kind of music appeals to people. It could just be that the music sounds good. However, that is not the sort of explanation that historians look for.
Historians would argue that rock appealed to the young people of the '50s because it was the opposite of the staid, calm lives that their parents wanted to lead. Their parents wanted lives that were calm and safe because they had just been through the Great Depression and WWII. As a result, they listened to music that was (according to the link below) "too inhibited, too class-conscious, and too slow."
Because the youth of the '50s felt this way, they wanted music that would shock their parents. They wanted to listen to uninhibited, fast music. Rock and roll fit the bill. Rock and roll's appeal, then, was a result of the growing gap in attitudes between the youth of the '50s and their parents.
Some of the music styles that arose in the United States in the 1950s became the dominant form of popular music in the world. One of these styles was called “Rock and Roll”. The highly rhythmic and sensual music of this era strongly influenced newly affluent postwar teenagers. Rock and Roll’s roots lay principally in rhythm and blues (R&B) and country music, both of which existed outside the mainstream of popular music in the 1950s. This music was new, out of the ordinary, and appealed to the younger generation. It provided an easy way for them to rebel out of the traditions and regulations of their parents. This type of music helped to promote people going out as groups of individuals rather than couples, which put less pressure on the people attending these kinds of events.